1. Field of the Invention
The present invention relates to a printing apparatus and a posture change correcting method for a print head and, more particularly, to a technique for reducing print position shift caused by a posture change of a print head while scanning.
2. Description of the Related Art
In a printing apparatus in which a print head scans a print medium so as to perform printing, the posture of the print head while scanning may be changed, which is caused by, for example, an incorporation error of a guide member for guiding the movement of the print head for scanning. The posture change of the print head of, for example, an ink jet system shifts the landing position of ink ejected from the print head on a print medium from a target position, and thus, shifts the position of an ink dot to be formed on the print medium. This is called print position shift.
Japanese Patent Laid-Open No. 2007-090875 discloses a method for reducing print position shift caused by the posture change of a print head. Specifically, a sensor for detecting the posture change of a print head is provided and the posture of the print head is corrected based on the detection result from the sensor by a piezoelectric element, so that print position shift is reduced.
However, in a case where the sensor detects the posture change of the print head, as disclosed in Japanese Patent Laid-Open No. 2007-090875, there arises a problem that the sensor detects only the posture change in a predetermined direction. More specifically, the detection of the posture change by the sensor disclosed in Japanese Patent Laid-Open No. 2007-090875 cannot cope with print position shift in a case where the combination of causes of posture changes in a plurality of directions induces print position shift in a predetermined direction.